How to Get "Call of Duty: Black Ops" Zombies Map Packs for the PS3

The PlayStation 3 (PS3) version of "Call of Duty: Black Ops" comes with three downloadable map packs. Each map pack contains one map for playing "Nazi Zombies," a game where you and a group of friends must hold out against waves of rampaging zombies for as long as you can. You must have a valid credit or debit card if you want to download the map packs, as well as have your PS3 connected to the PlayStation Network via its Ethernet connection.